VLSI testing is being pushed to the high-level based technology. In this paper a Verilog Register transfer level Model (VRM) for integrated circuits is proposed. The model provides a text format file, which is convenient and more practical for developing succeeding Register Transfer Level (RTL) test tools, such as fault simulation, test patt generation and so forth. Based on the VRM, an RTL concurrent fault simulation approach is presented. After RTL fault models and super faults defined, the concurrent fault simulation algorithm is given. The corresponding RTL concurrent fault simulator,VFSim, was implemented. The initial experiments show that the RTL fault simulator is efficient for VLSI circuits.